1. Field of the Invention
This application is directed to a process for increasing the treating capacity of an adsorbent bed of a finishing unit for oils of lubricant viscosity and for improving the quality of the oil treated therein.
2. Description of the Prior Art
It is known to selectively sorb compounds of low polarity from mixtures with compounds of the same or greater polarity by using a crystalline alumino-silicate; U.S. Pat. No. 3,732,326. Anhydrous acidic zeolite aluminosilicates (containing cerium ions) are known to be useful as catalysts in the alkylation of isoparaffins with olefins; British Pat. No. 1,209,942.
Further, acid resistant, heat resistant molecular sieves prepared from volcanic tuff are claimed to be useful for removing low molecular weight contaminants, such as carbon dioxide and ammonia from organic substances, E. Gaeroeg et al. (Inst. High Pressure Res., Budapest) Brenn st. Chem. 50 No. 8: T 59 (August, 1969). Also acidic impurities are claimed to be selectively adsorbed from a gas stream with an activated zeolitic molecular sieve having adsorbed ammonia; the impurity may be CO.sub.2, CS.sub.2, H.sub.2 S, NO.sub.2 or C.sub.1 -C.sub.5 alkylmercaptans; Belgium Pat. No. 729, 768-69. Treating liquid hydrocarbons by percolating them through clay is also known.
Lubricating oil base stocks, especially turbine oils contain compounds with heteroatoms such as nitrogen and sulfur. The presence of small amounts of sulfur compounds in such hydrocarbons tends to be desirable. However, compounds containing nitrogen and other organic or polar moieties are usually not desirable. Therefore, a process which removes such undesirable compounds from various hydrocarbon feedstock, e.g., hydrocarbon oils of lubricating viscosity is highly desirable.